Wenqing Liang

Porphyrin-based metallopolymers: synthesis, characterization and pyrolytic study for the generation of magnetic metal nanoparticles

Metallopolymers with different metal centers, pendant groups and linkages exhibit diverse structures and properties, thus giving rise to versatile applications, e.g., as emissive and photovoltaic materials, optical limiters, materials for nano-electronics, information storage, nanopatterning and sensing, macromolecular catalysts and artificial enzymes, and stimuli-responsive materials. Recently, metallopolymers as precursors to generate monometallic or metal alloy nanoparticles are of great interest owing to their advantages of ease of processability, atomic level mixing, and stoichiometric control over composition. By taking advantage of the template effect of porphyrin compounds, a series of monometallic and heterobimetallic polymers are synthesized which are characterized by NMR, IR, HRMS, EA, GPC and TGA, respectively. Photophysical properties of these metallopolymers are also studied by UV-vis spectroscopy. Pyrolytic treatment of these metallopolymers generates various magnetic monometallic and metal alloy nanoparticles which can be used in data storage, catalysis, biomedicine, etc.

Efficient blue fluorescent organic light-emitting diodes based on novel 9,10-diphenyl-anthracene derivatives

A series of novel 9,10-di(naphthalen-2-yl)anthracene (ADN) derivatives were designed and synthesized as blue fluorescent emissive materials by inducing diverse aromatic groups to the C-2 position of ADN. UV-Vis absorption, fluorescence emission spectroscopy and cyclic voltammetry (CV) were carried out to generally investigate the relationships between the physical properties and molecular structures. Moreover, four non-doped OLED devices adopting OCADN, FA3PADN, FA4PADN and OC4PADN as emitting materials were fabricated to study their electroluminescence (EL) performances. Among them, a device based on OCADN exhibited highly efficient sky-blue emission with a current efficiency of 2.25 cd A−1, power efficiency of 1.13 lm W−1 and CIE(x, y) coordinate of (0.16, 0.30) at 8 V. In addition, the device of OC4PADN showed efficient blue emission with a CIE(x, y) coordinate of (0.16, 0.14) at 8 V.

Synthesis and photoelectric properties of a solution-processable yellow-emitting iridium(III) complex

A solution-processable yellow-light-emitting heteroleptic phosphorescent Ir(III) complex of (CzhBTZ)2Ir(fpptz) [CzhBTZ: (2-[2-(6-(9-carbazolyl)hexyl)phenyl]benzothiazole) fpptz: (2-(5-(4-fluorophenyl)-2H-1,2,4-triazol)-3-yl)] was synthesized. Its photophysical, thermal and electroluminescence properties were investigated. Phosphorescent organic light-emitting diodes (PhOLEDs) using (CzhBTZ)2Ir(fpptz) doping in (4,4′-bis(N-carbazolyl)-1,1′-biphenyl) as the emitting layer were prepared by spin-coating with a maximum peak at 533 nm, and International Commission on Illumination (CIE) coordinates of (0.42, 0.56).

Fluorene-based hyperbranched copolymers with spiro[3.3]heptane-2,6-dispirofluorene as the conjugation-uninterrupted branching point and their application in WPLEDs

A series of white light-emitting hyperbranched copolymers (P2–P5) consisting of polyfluorene/4,7-dithienyl-2,1,3-benzothiadiazole (DBT) branches and spiro[3.3]heptane-2,6-dispirofluorene (SDF) conjugated branching point have been synthesized and fully characterized. The effects of the branching degree on the thermal, photoluminescent and electroluminescent properties of the copolymers were investigated. The results suggest that the branching point helps to enhance both the thermal and spectral stabilities of the hyperbranched copolymers, and retain the energy transfer efficiency from fluorene to DBT unit. Efficient hyperbranched copolymer-based single-layer devices are achieved with CIE coordinates located at near (0.33,0.33). Especially, a device based on P4 (10 mol% of SDF) exhibits a doubled efficiency and 5.5-fold increase in luminance compared to the device based on the linear reference.

Hyperbranched fluorene-alt-carbazole copolymers with spiro[3.3]heptane-2,6-dispirofluorene as the core and their application in white polymer light-emitting devices

A series of hyperbranched copolymers with fluorene-alt-carbazole as the branches and three-dimensional-structured spiro[3.3]heptane-2,6-dispirofluorene (SDF) as the core were synthesized by one-pot Suzuki polycondensation. 4,7-Dithienyl-2,1,3-benzothiadiazole (DBT) as the orange-light emitting unit was introduced into the backbones to obtain white-light emission. The thermal, photoluminescent (PL), electrochemical and electroluminescent (EL) properties of the copolymers were investigated. The copolymers show great thermal stabilities by the introduction of a carbazole moiety. Besides, the HOMO energy levels of the copolymers were enhanced and the hole injection was improved because of the hole-transporting ability of the carbazole unit. The hyperbranched structures suppress the interchain interactions efficiently, and help to form amorphous films. The copolymers exhibit efficient EL performance as a result of the hyperbranched structure with the incorporation of the carbazole moiety. A quite low turn-on voltage of 5.3 V, a maximal luminance of 7409.5 cd m−2 and a luminous efficiency of 4.27 cd A−1 were achieved with a CIE coordinate of (0.32, 0.26) for the PFCzSDF10DBT10 (10 mol% of SDF and 0.1 mol% of DBT) device. The hyperbranched framework based on fluorene-alt-carbazole branches and SDF core are attractive candidates for solution-processable white polymer light-emitting device (WPLED) applications.